At temperatures near 350, 500, 650, and 900 °C the plasticity of vanadium is diminished, and the strength increased owing to dynamic deformation aging.

The mechanical properties of Nb were studied in the temperature interval from 20 to 900 deg C. It is shown that at an expansion rate of 1.6 x 10/sup -3/ sec/sup -1/ at temperatures of 300, 400, and 550 deg C, the maximum strength properties and the corresponding ductility maxima were detected. The height of the maxima at 300 and 550 deg C depends on the concentration of oxygen and nitrogen. The continuous change of the mechanical properties of Nb with temperature is connected with deformation dynamic aging. (tr-auth)

The effects of oxygen and nitrogen impurities on the nature of the temperature and strength--ductility properties of niobium was studied. Niobium of 99.8% purity was used which contained metallic impurities of 0.09% Ta and 5 x 10/sup -3/% W and Fe, and interstitial impurities of 2 x 10/sup -3/% H/sub 2/, 5 x 10/sup -3/% O/sub 2/ and 2.6 x 10/su p -3/% Nsub 2/. The mechanical properties of niobium were studied in the 20 to 900 deg C interval where it was shown that at a strain rate of 1.6 x 10/sup -3/ s, at 300, 400, and 550 deg C, maximum strength properties and minimum ductility are observed. Height of the maximums at 300 and 550 deg C depends on the concentration of oxygen and nitrogen. The smooth change in the mechanical properties of niobium with temperature is associated with the deformation dynamics of aging. (JPRS)

Refractory metals are very sensitive to their surface condition. Removing microcracks, scratches, and other surface defects leads to an increase in their strength and ductility and lowers the ductile-to-brittle transition temperature [1], On the other hand, working media, surface films, and special coatings affect the surface condition and, consequently, mechanical properties of metals [2, 3], Especially interesting in this context are studies of the effect of thimetal coatings leading to an increase in the strength and ductility of metals and alloys.

Abstract : The proposed method of thermal conductivity determination is free of radiative loss and changes in temp. gradient occurring in the measurement. The method permits the measurement of thermal conductivity in samples of simple geometrical form up to temperatures of failure. The thermal conductivity coefficient of Nb was measured at 1000-1600C. The electrical resistivity of Nb increases from 56 at 1000C to 74.7 microhm-cm. at 1600C. (Author)